Ok, so If Old Man Winter and Entropic sphere have a 3 second delay when I press the 4 button, Do the Figurehead and Horn powers that summon an entity to attack for me also have a 3 second delay?

I know that the direct fire attacks affect the target immediately, just like the cannon.

The answer technically remains the same . . . it depends on the power. Really, the best way to determine this is to . . . use the power! After you press the button, see when the damage numbers then show for the attack. In most cases it should be pretty clear.